A coaster is a small, flat object typically placed under a drinking glass, cup, or bottle to protect surfaces from moisture, heat, or scratches caused by condensation, spills, or hot beverages. Coasters come in a wide variety of materials, shapes, and designs, making them both functional and decorative. Common materials include cork, wood, ceramic, stone, metal, silicone, and paper. Some coasters are disposable, while others are reusable and designed to last for years. They often feature decorative elements such as patterns, logos, or humorous sayings, making them a popular choice for personalizing spaces like homes, offices, and cafes.